Summary On 09 June 1999, the Canadian-registered self-unloading bulk carrier ALGOBAY was exiting the Poe Lock downbound, at Sault Ste. Marie, Michigan. As the vessel passed the eastern approach wall, the unloading boom was raised to correct a one and one-half degree list to port. The boom swung out of control to port and knocked down five light standards on the approach wharf. Structural damage to the boom was minor; however, the hydraulic slewing system was extensively damaged. There were no injuries or pollution as a result of the occurrence. Ce rapport est galement disponible en franais. Other Factual Information History of the Voyage The ALGOBAY departed Superior, Wisconsin, at 1710 eastern daylight time, 07 June 1999, with a cargo of 26,137 tons of coal.[2] On the morning following departure, as the vessel crossed Lake Superior, the chief engineer, with the authorization of the master and shore management, shut down the port main engine for unscheduled repairs. At 1745, the vessel advised Vessel Traffic Services (VTS) that the passage through the locks at Sault Ste. Marie and the St. Marys River would have to be conducted with one engine. Permission was granted by the United States Coast Guard (USCG) and Sault Ste. Marie harbour master. Before arriving at the Sault locks, the vessel had developed a one and one-half degree list to port. Concerned with low water levels in the St. Marys River and the 10 cm of extra draught the list would have created, the master ordered the second officer to lift the unloading boom and slew it to starboard as the vessel departed Poe Lock at 0225 on June 9. In doing this, it was hoped that ballast water remaining on board in the No. 3 port ballast tank would be displaced to starboard and the list corrected. As the boom was being lifted from its saddle, it began swinging to port. Despite attempts by the second officer to check its movement with the slewing controls, the boom accelerated outwards until it contacted the front of the accommodation at an angle of 90 degrees to the vessel. At the time of the occurrence, the vessel was travelling at four knots, approximately 50 m from the lower approach wall to Poe Lock. As the vessel continued forward, the boom made contact with five light standards. Upon seeing the boom swing fully to port, the master immediately put the engine to full astern. The single engine, running full astern, was overloaded and the watchkeeping engineer informed the master that he would have to reduce power. In an attempt to prevent further damage to the boom and wharf, the second officer topped up the boom until he was prevented from lifting further by the accommodation structure. The master ordered the stern and both bow anchors dropped to help arrest the vessel's forward movement and to prevent it from swinging towards other vessels moored at the adjacent USCG base. Once the vessel was stopped, and the boom recovered, the ALGOBAY proceeded to tie up on the lower wall of the MacArthur Lock with the assistance of two tugs. Damage to the Vessel and Dock Five light standards on the approach wharf were knocked down and damaged. The unloading boom suffered extensive damage to its port forward and starboard after slewing cylinders when air trapped in the hydraulic slewing rams compressed and fractured the cylinders. The unloading hopper was damaged, as were the starboard catwalk and lower longitudinal, which were set in at the point of contact with the light standards. Voyage Repairs During the ballast voyage to Superior, it had been discovered that the No. 1 cylinder head on the port main engine was leaking cooling water from a jumper between the block and cylinder head. Not wanting to delay the vessel's departure from Superior by carrying out repairs there, the chief engineer and master agreed that the port main engine would be shut down after departure to make the repair while the vessel was under way. It was anticipated that the repairs would take approximately 12 hours. At 0800 on June 8 the repairs were begun; however, while removing the cylinder head from the engine, it was discovered that a cylinder head stud was broken and would have to be replaced. The chief engineer, who had previous experience with this type of repair, informed the master of the situation and revised his estimated completion time upwards to 24 hours. As the work would be conducted near the running starboard main engine, the chief engineer suggested that the vessel be stopped in Lake Superior for the duration of the repair. In consultation with the master and chief engineer, the company engineering superintendent decided that the vessel should proceed towards Sault Ste. Marie in case further shore support was needed for the repairs. During the previous sailing season, the vessel had operated for several months on one engine, including during passages through the American locks at Sault Ste. Marie. On the morning the main engine repairs were begun, the head tunnelman asked for and received permission from the chief engineer to change the oil in the hydraulic slewing system of the cargo unloading boom. Due to the relatively short voyages undertaken by the vessel since the beginning of the 1999 season, this scheduled preventative maintenance procedure was overdue. During the longer trip from Superior, Wisconsin, to Nanticoke, Ontario, the cargo unloading boom would not be used and this period was adequate to complete the maintenance. After the deck department had transferred cargo to correct a slight port list, and had run spillage, the head and assistant tunnelmen drained the hydraulic oil from the slewing system and proceeded to clean the hydraulic tank. It is reported that the chief engineer opened the breaker in the engine-room and tagged it as being unavailable for service; however, the bridge was not informed of the maintenance work being conducted. At 2000 the head tunnelman reported to the chief engineer that he had finished draining and cleaning the hydraulic system. The chief engineer indicated that, because the head tunnelman was unfamiliar with the procedure to bleed the air from the hydraulic system, he decided to wait until daylight the following morning. The chief engineer, assuming that the system had been refilled with oil, returned to the engine-room, removed the tag from the slewing system breaker and turned it back on. The oil, however, had not been refilled and the slewing system was still unserviceable. The unloading boom topping lift system was actuated directly by an electric motor, and operated independently of the hydraulic slewing system. Although the slewing system was fitted with an interlock that prevented the slewing pump from starting without oil in the hydraulic tank, the interlock was not tied into the topping lift controls. Engine-Room Staff Experience At the time of the occurrence, the chief engineer, third engineer, and one mechanical assistant were the only regular engine-room staff members on board. All other staff members were relieving crew, unfamiliar with the vessel. The head tunnelman was a vacation relief and, although he had experience on other self-unloaders, he was relatively unfamiliar with the unloading equipment on the ALGOBAY. On-board Procedures Although a video on electrical tag-out procedures was available on board, the head tunnelman had not viewed it when he came on board three trips before the occurrence trip. Binders containing tag-out procedures pursuant to the International Safety Management (ISM) Code were on board, but were stored on the bridge and in the master's and the chief engineer's cabins, and not readily available for general reference by the crew. Notwithstanding company standing orders requiring the deck and engine-room departments to inform each other of machinery being taken out of service, the deck and engine-room departments did not regularly exchange information concerning routine maintenance that could affect the operation of the vessel. As well, within the engine-room, the tunnelmen reported directly to the chief engineer and did not provide information on their activities to the watchkeeping engineers. No formal procedures were in place for the operation of the unloading boom. Unless electrical power was needed to run the main unloading belts, the engine-room was not informed when the boom was to be raised or slewed. No pre-start checklist was used to verify the readiness of the unloading boom for service (in particular the oil level in the hydraulic slewing system). The unloading system was equipped with two lockout keys controlling the unloading belt drive motors and the slewing/hoisting system respectively. It was the practice to leave these keys in their respective key switches in the unloading control room when the system was not in use.